docs: def get_bounds(self, which, dimension):
          """``get_bounds('lower', 8)`` returns the lower bounds in 8-D"""
          if which == 'lower' or which == 0:
              return self._get_bounds(0, dimension)
          elif which == 'upper' or which == 1:
              return self._get_bounds(1, dimension)
          else:
              raise ValueError("argument which must be 'lower' or 'upper'")